Conventionally, a spoiler on an aircraft wing is driven by a spoiler driving mechanism that includes a hydraulic actuator (refer to, for example, Japanese National Phase Patent Publication No. 2008-529871). FIG. 5 shows an example of a spoiler driving mechanism, and shows a state of a flap 102 and a spoiler 104 on a wing 100 when the aircraft is cruising by solid lines. The positions of the flap 102 and the spoiler 104 shown by the solid lines may be referred to as neutral positions.
A hydraulic actuator 106 of the spoiler driving mechanism is coupled to the spoiler 104. The spoiler 104 rises and falls based on a reciprocating movement of a piston rod 108 of the hydraulic actuator 106. When the flap 102 and the spoiler 104 are deployed into a high lift configuration, as shown by the alternate long and two short dashed lines, the flap 102 is caused to fall from the neutral position by an unillustrated actuator, and the spoiler 104 is caused to fall from the neutral position by the hydraulic actuator 106. The spoiler 104 partially occupies a gap G defined between the wing 100 and the flap 102.
When reducing aircraft speed, the spoiler 104 is raised from the neutral position by the hydraulic actuator 106 as shown by the broken lines in FIG. 5. The spoiler 104 thereby serves as air resistance to reduce aircraft speed.
The spoiler 104 thus rises and falls in a driving range DS from the position shown by the long and two short dashed lines to the position of the broken lines, while the flap 102 rises and falls in a driving range DF from the position shown by the long and two short dashed lines to the neutral position, so that an overlapping region R is created in which the driving range DS of the spoiler 104 and the driving range DF of the flap 102 overlap.